In recent years, the cosmetic and medical uses of collagen materials have increased dramatically. For example, collagen compositions are now commonly used in facial enhancement procedures such as augmentation of the lips or filling in of wrinkles via collagen injection. Collagen is also used to fill voids in the face resulting from the removal of skin cancers such as basal cells or melanoma. U.S. Pat. Nos. 5,527,856; 5,550,187; and 5,752,974 relate to collagen compositions for various applications. Medical procedures using collagen have also been developed to increase the competency of sphincter muscles located throughout the body, which involves injection of collagen directly into the sphincter muscles. U.S. Pat. No. 5,490,984. This technique has been shown to alleviate anorectal and/or urinary incontinence.
Despite its recognized benefits, the use of collagen in medical applications is not without drawbacks. First, there is only a limited supply of useful collagen, as it must be procured from a xenogenic and/or allogenic donor. With respect to xenogenic collagen, it has been shown to induce an acute antigenic response, which can cause deleterious symptoms in the recipient and ultimately leads to the rapid rejection of the collagen material. While, allogenic collagen has been shown to have a lower rejection rate, it does not retain its shape well and still is ultimately absorbed. In sum, the medical/cosmetic uses of collagen typically only provide a temporary result.
Accordingly, efforts are being made to develop injectable collagen based materials that are not rejected and which have increased retention in the body and a lower absorption rate than current commercially available products.